Compression.
TV has a whole lot more of it than movies do.
Then, to boot, you are applying Dyn volume only to cable as well.
I almost never listen to movies as quietly as -15 db. Probably 1 out of every 50 movies. Every once in a while, I put on some old B/W movie from the 50s, and it runs pretty hot. I'd say it's probably closer to 1/100 movies, and for those IIRC it's set to something like -20db.